10/1/2009
NEWS BRIEFS
Quality, Testing Scrutinized in Bolt Problems on Navy Submarines

A month after the U.S. Navy revealed that improperly installed bolts on weapons-handling systems would delay or sideline at least four of its submarines, Northrop Grumman’s Newport News shipyard continues its investigation.

Early indications suggest Northrop could overhaul its quality assurance and testing programs, both of which failed to detect problems with the fasteners, reports the Daily Press of Hampton Roads, VA.

Shipyard general manager Matt Mulherin told the Daily Press that the incident has caused embarrassment.

“It’s really looking at how do we plan, implement engineering,” Mulherin stated. “We’re asking ourselves, ‘What do we have to do to keep from repeating these things?’ ”

Workers at Northrop Grumman’s Newport News shipyard reportedly mishandled the fasteners that hold together tracks on which weapons are moved in the sub’s torpedo room.

“During the final alignment of the forward and aft weapon cradle tracks aboard the Missouri, several bolts, bolt holes and fasteners were found that did not meet specifications. Specifically, the shipbuilders have found improperly drilled and machined bolt holes, bolts that had been improperly machined, and fasteners that were not installed and tightened properly,” according to a written statement from Naval Sea Systems Command (NAVSEA).

The application of non-specification bolts, bolt holes and fasteners could result in a “misalignment of the weapons-handling equipment that could prevent the movement of weapon cradles within the torpedo room, and could compromise the integrity of the weapons handling system in a shock event,” according to a NAVSEA statement.

Inappropriate use of the fastener adhesive Loctite is also reportedly part of the issue.

Northrop Grumman described the problem as including “use of the incorrect grade of Loctite; close tolerance bolts that were modified without the proper use of appropriate technical direction (certain shanks tapered, thread ends cut short); close tolerance bolts that did not meet the diametrical clearance requirements for the respective hole; truss tapped holes that were damaged and nonconforming threads,” the Navy Times reports.

The Navy confirmed the problems on the $2 billion Virginia-class submarines the North Carolina, New Mexico, Missouri and California. ©2009 GlobalFastenerNews.com